new android, try it Red Magic 9pro

No VoLTE, VoNR, or VoWiFi support for the US.  Asian focuses devices, even using global ROM's, are almost always lacking the compatibility for VoLTE, which is required to make and receive calls on any US carrier network.  T-Mobile uses the stock implantation of Android's VoLTE, VoNR, and WiFi Calling, which is not available on Chinese market focused devices and US carriers do not offer 3G service to fall back on.

Tmobile doesn't sell that phone and some phones can't be activated on Tmobile’s network if they don't have approved VoLte standards.

@syaoran